1. Technical Field of the Invention
The present invention relates generally to a cooling mechanism for a battery pack mounted in hybrid vehicles, and more particularly to an air cooling mechanism designed to introduce outside air to cool battery cells, etc., in a battery pack.
2. Background Art
In order to ensure high efficiency in driving an electric motor that is a drive source, hybrid vehicles usually sets the voltage high, which is to be applied to the motor, so that a high current flows through the motor during operation thereof. This will result in a rise in internal temperature of a battery pack in which batteries (also called battery modules) are disposed. Japanese Patent First Publication, as listed below, teaches a cooling system for a battery pack mounted in such a hybrid vehicle. The hybrid vehicle, as disclosed in this publication, is equipped with a step formed by protruding a floor panel under seats for passengers and has the battery pack and a fuel tank arranged in a width-wise direction of the vehicle below the step. To cool inside the battery pack by introducing outside air through a cooling fan, the battery pack has an air inlet formed on a portion of an upper surface thereof closer to the rear of the vehicle and an air outlet formed on a portion of the upper surface closer to the front of the vehicle.    Japanese Patent First Publication No. 2001-138753.